Next-to-next-to-leading order gravitational spin-orbit coupling via the effective field theory for spinning objects in the post-Newtonian scheme

TL;DR

This paper derives the gravitational spin-orbit interaction potential at the third and a half post-Newtonian order for spinning compact objects using an effective field theory approach, including automation and comparison with ADM results.

Contribution

It provides the first Lagrangian form of the next-to-next-to-leading order spin-orbit potential and automates the EFT computations for higher order post-Newtonian corrections.

Findings

Derived the 3.5PN spin-orbit Hamiltonian in Lagrangian form.

Automated EFT calculations for complex post-Newtonian terms.

Confirmed agreement with ADM Hamiltonian results.

Abstract

We implement the effective field theory for gravitating spinning objects in the post-Newtonian scheme at the next-to-next-to-leading order level to derive the gravitational spin-orbit interaction potential at the third and a half post-Newtonian order for rapidly rotating compact objects. From the next-to-next-to-leading order interaction potential, which we obtain here in a Lagrangian form for the first time, we derive straightforwardly the corresponding Hamiltonian. The spin-orbit sector constitutes the most elaborate spin dependent sector at each order, and accordingly we encounter a proliferation of the relevant Feynman diagrams, and a significant increase of the computational complexity. We present the evaluation of the interaction potential, going over contributing Feynman diagrams. The computation is carried out in terms of the nonrelativistic gravitational fields, together with the various gauge choices included in the effective field theory for gravitating spinning objects, which optimize the calculation. In addition, we automatize the effective field theory computations, and carry out the automated computations in parallel. Such automated effective field theory computations would be most useful to obtain higher order post-Newtonian corrections. We compare our Hamiltonian to the ADM Hamiltonian, and arrive at a complete agreement between the ADM and effective field theory results. We provide complete gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to third and a half post-Newtonian order. The derivation presented here is essential to obtain further higher order post-Newtonian corrections, and to reach the accuracy level required for the successful detection of gravitational radiation.